media: dvb: return -EREMOTEIO on i2c transfer failure.

Currently when i2c transfers fail the error return -EREMOTEIO
is assigned to err but then later overwritten when the tuner
attach call is made.  Fix this by returning early with the
error return code -EREMOTEIO on i2c transfer failure errors.

If the transfer fails, an uninitialized value will be read from b2.

Addresses-Coverity: ("Unused value")

Fixes: fbfee868 ("V4L/DVB (5651): Dibusb-mb: convert pll handling to properly use dvb-pll")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>